package com.hsq.servlet;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

/**
 * 替换HttpServlet，根据请求的最后一段路径进行方法的分发
 */

public class BaseServlet extends HttpServlet {

    // 根据请求的最后一段路径进行方法的分发
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // 1.获取请求路径
        String uri = req.getRequestURI();  // brand-case/brand/selectAll

        // 2.获取最后一段路径，也就是方法名
        int index = uri.lastIndexOf('/');
        String methodName = uri.substring(index + 1);

        // 3.执行方法
        // 3.1 获取BrandServlet UserServlet 等字节码对象 Class

        /*
         * System.out.println(this);
         *
         * this：谁调用我（this 所在的方法），我（this）代表谁
         * 这里的this代表BrandServlet
         */

        Class<? extends BaseServlet> cls = this.getClass();

        // 3.2 获取方法method对象
        try {
            Method method = cls.getMethod(methodName, HttpServletRequest.class, HttpServletResponse.class);
            // 3.3 执行方法
            method.invoke(this, req, resp);
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }

    }
}
